From the age of 45, fewer and fewer follicles mature in the ovaries and menstrual cycles often proceed without ovulation. The consequence: without ovulation, no corpus luteum is formed; the level of the corpus luteum hormone (progesterone) drops. At this time, however, sufficient estrogens are still produced. As a result, the uterine lining continues to grow and menstrual bleeding takes place as usual. As a result, the uterine lining continues to grow and menstrual bleeding takes place as usual.

In the following years, estrogen production also reduces. The bleeding becomes more and more irregular until it finally stops completely. The last bleeding is called menopause. After that, pregnancy is no longer possible. On average, menopause occurs at age 51. Menopause can only be determined retrospectively: If menstruation is absent for a whole year, the last bleeding was menopause. If this event occurs before the age of 40, there is “premature menopause”.

The timing of the last menstrual period is – according to current knowledge – hereditary and occurs at about the same age in mothers and daughters. Also, the onset of menopause is likely to be influenced by the number of births, which is why it starts earlier on average for women in countries with higher fertility rates.

Also debated is the extent to which and whether heavy smoking leads to early onset menopause. The length of the cycle in case of overweight or underweight may also influence the onset.